Personal Formularies of Primary Care Physicians Across 4 Health Care Systems

Abstract

IMPORTANCE More conservative prescribing has the potential to reduce adverse drug events and patient harm and cost; however, no method exists defining the extent to which individual clinicians prescribe conservatively. One potential domain is prescribing a more limited number of drugs.Personal formularies-defined as the number and mix of unique, newly initiated drugs prescribed by a physician-may enable comparisons among clinicians, practices, and institutions.OBJECTIVES To develop a method of defining primary care physicians' personal formularies and examine how they differ among primary care physicians at 4 institutions; evaluate associations between personal formularies and patient, physician, and practice site characteristics; and empirically derive and examine the variability of the top 200 core drugs prescribed at the 4 sites. DESIGN, SETTING, AND PARTICIPANTSThis retrospective cohort study was conducted at 4 US health care systems among 4655 internal and family medicine physicians and 4 930 707 patients who had at least 1 visit to these physicians between January 1, 2017, and December 31, 2018. EXPOSURES Personal formulary size was defined as the number of unique, newly initiated drugs. MAIN OUTCOMES AND MEASURESPersonal formulary size and drugs used, physician and patient characteristics, core drugs, and analysis of selected drug classes. RESULTSThe study population included 4655 primary care physicians (2274 women [48.9%]; mean [SD] age, 48.5 [4.4] years) and 4 930 707 patients (16.5% women; mean [SD] age, 51.9 [8.3] years). There were 41 378 903 outpatient prescriptions written, of which 9 496 766 (23.0%) were new starts. Institution median personal formulary size ranged from 150 (interquartile range, 82.0-212.0) to 296 (interquartile range, 230.0-347.0) drugs. In multivariable modeling, personal formulary size was significantly associated with panel size (total number of unique patients with faceto-face encounters during the study period; 1.2 medications per 100 patients), physician's total number of encounters (5.7 drugs per 10% increase), and physician's sex (−6.2 drugs per 100 patients for female physicians). There were 1527 unique, newly prescribed drugs across the 4 sites. Fewer than half the drugs (626 [41.0%]) were used at every site. Physicians' prescribing of drugs from a pooled core list varied from 0% to 100% of their prescriptions.CONCLUSIONS AND RELEVANCE Personal formularies, measured at the level of individual physicians and institutions, reveal variability in size and mix of drugs. Similarly, defining a list of commonly prescribed core drugs in primary care revealed interphysician and interinstitutional differences. Personal formularies and core medication lists enable comparisons and may identify outliers and opportunities for safer and more appropriate prescribing.

Pharmaceutical Simplification: Killing Two Birds with One Stone

“…In fact, using only a few drugs and learning to use them well is considered one of the principles of conservative prescription, which can reduce adverse drug events and costs . Clinicians who prescribe fewer drugs likely develop more expertise with each substance and their patients may have a lower frequency of adverse reactions and inappropriate medication use . Going one-step further, we believe that the “rational use of medicines” defined in 1985 by the WHO needs to be modernized to incorporate “One-Health” philosophy …”

“…6 Clinicians who prescribe fewer drugs likely develop more expertise with each substance and their patients may have a lower frequency of adverse reactions and inappropriate medication use. 7 Going one-step further, we believe that the "rational use of medicines" defined in 1985 by the WHO needs to be modernized to incorporate "One-Health" philosophy. 8 We argue that pharmaceutical simplification may also be taken into account as a measure to tackle pharmaceutical pollution.…”

Missing Funding/Support

“…In the Original Investigation titled “Personal Formularies of Primary Care Physicians Across 4 Health Care Systems,” published July 15, 2021, information on Funding/Support was missing, and the Role of the Funder/Sponsor paragraph needed to be revised. This article has been corrected …”